The invention relates to improvements in rotor for affixation to the lower ends of vertical, motor-driven shafts such as found in mixers or liquifiers commonly used for the preparation of milkshakes, malts, ice cream drinks and the like. A mixer shaft of this type will turn at high speed, usually in the order of 3,000 to 10,000 RPM as a suitable container is positioned in such manner that the shaft and rotor extend within the container to mix the contents. Many forms of rotors are and have been used, all designed to produce various types of mixing actions. In one example in particular, such as disclosed in the U.S. patent to Moskowitz, U.S. Pat. No. 4,305,670, the rotor is in the form of a truncated conical member mounted coaxially on the end of the shaft and having upwardly convergent ribs said to produce a certain mixing action. The rotor in the patent is made of a plastic material and has a lower annular edge so as to avoid damaging the container, especially during removal of the container from the shaft while the shaft is still turning at high speed.
According to the present invention, an improved rotor is provided having diametrically opposed blades that extend in upwardly and outwardly divergent fashion from the lower end of the shaft. Blades of this type are subject to substantial centrifugal force and would tend to extend radially during operation, increasing the possibility of damaging the container and even causing injury to the hand of the user holding the container in the use of paper or paper-like containers. To avoid these possibilities and to augment the mixing action, the improved rotor includes a disk having a central opening receiving the shaft and disposed in a plane normal to the shaft axis and spaced above the lower end of the shaft. The periphery of this disk is affixed, as by welding in the instance in which the material is stainless steel, for example, to the upper ends of the divergent arms. The disk has an annular flange surrounding the attached upper ends of the blade arms and presents a smooth annular edge or surface. The blade arms lie on or within the surface of an inverted truncated right regular cone having the disk as its base. Thus the blade arms do not project beyond the surface of this cone and therefore cannot damage the container even if contact is made.
The rotor can be constructed for use with mixers of known designs and is easily attached for use and detached when necessary. Further features will appear as the disclosure continues.